Subjective Fatigue, Influencing Variables, and Consequences in Chronic Obstructive Pulmonary Disease
Fatigue is a common symptom of chronic obstructive pulmonary disease (COPD), but little is known about the specific nature of COPD-related fatigue and its impact on daily life.Objectives:
To (a) describe characteristics of fatigue in people with COPD and (b) test a theoretically and empirically supported model of the relationships among subjective fatigue, dyspnea, functional performance, anxious and depressed moods, and sleep quality in people with COPD.Methods:
A cross-sectional descriptive study was conducted with 130 people with moderate to severe COPD. Measures included the following: a Numerical Rating Scale (NRS) for frequency, intensity, and distress of fatigue and dyspnea; Fatigue Assessment Instrument (FAI); Chronic Respiratory Disease Questionnaire (CRQ); Profile of Mood States (POMS); Pittsburgh Sleep Quality Index (PSQI); Functional Performance Inventory (FPI); and spirometry. Path analysis was used to examine the relationships among variables.Results:
Participants reported moderate amounts of fatigue, which was described as situation-specific, had considerable consequences, and was responsive to rest and sleep. Dyspnea was slightly greater than fatigue, as measured by the NRSs (p <.001), and there was a strong relationship between fatigue and dyspnea (r =.74, p < .001). Dyspnea, depressed mood, and sleep quality accounted for 42% of the variance in subjective fatigue. Fatigue, dyspnea, airflow obstruction, and anxious mood accounted for 36% of the variance in functional performance.Conclusions:
Fatigue is an important problem that affects performance of daily activities in people with COPD. The relationships or interactions that exist among fatigue and other symptoms are complex.